During an oil drilling process, debris (comprised of water, oil, stone, soil, metal fragments, mud and other components) is generated and stored in a pond adjacent to the drilling rig as sludge. This sludge must be treated according to industry standards set for maximum contaminant levels. These concerns stem from the potential adverse health effects of the contaminated water reentering the aquifer. The contaminated water, which is removed, must be trucked to disposal areas and pumped below the aquifer into detention areas, which are then sealed. Contaminated water removal has conventionally been a slow process, as the contaminants must be removed before transport. The only method currently available for removing contaminants from the water uses a sock type filter. This method is slow and cumbersome and requires many changes of the filter, causing serious time delays when filling the transport trucks.
While other types of water filters are available in different industries, the sock method is the only technique which has been acceptable to date for the filtering of contaminants from drilling sites. However, as mentioned previously, frequent filter changes are required, substantially slowing the transport process. Further, following scheduled filter replacements is crucial to eliminate the possibility of contamination, but not knowing the volume of sludge in the water does not allow for regular filter replacements. Thus, the operator must wait until the filter clogs, before replacing the filter. This slows the filtering process, substantially increasing the waiting time and operating costs.
One of the key difficulties faced in using the sock method is the complexity of the contaminated water. The water may contain particles of varying sizes, oil and tar. Filter life is dependent on how much of these components are present in the contaminated water and there is no easy way to segregate out the most damaging components to improve filter life.